This invention relates to a membrane support apparatus which includes a porous membrane and a support structure for the porous membrane. More particularly, this invention relates to a membrane support apparatus wherein one or more membranes are sealed in position between a base section and a top section by a plurality of peripheral seals.
Prior to the present invention, membrane support apparatus, including filtration apparatus have been provided which comprise a porous membrane such as a microporous membrane positioned between and sealed at its periphery between a base section and a top section. Inlet means are provided for introducing a liquid sample in the space between the top section and the base section and an outlet means is provided in the base section so that a liquid passes through the membrane from which is deposited on the membrane a filtrate or a solute component of the liquid. The remaining liquid is removed from the apparatus through the outlet. The membrane is sealed between the top section and the base section in a manner to prevent liquid from by-passing the membrane. That is, sealing is effected so that all of the liquid introduced is passed through the membrane prior to passing through the outlet. The membrane can be sealed to the internal peripheral surface of the base section or the membrane can be sealed to both the top section and the base section and between the two sections. The membrane can be heat sealed or solvent bonded to the base section as disclosed in U.S. Pat. No. 4,501,663 or the membrane can be ultrasonically welded between the base section and the top section as disclosed, for example in U.S. Pat. No. 4,640,777. With prior art devices, the weld or seal is effective only up to moderate pressure, for example between about 50 and 75 psi for polyethylene devices and between 75 and 100 psi for devices made from a polycarbonate-polyester melt alloy for a typical 25 mm diameter device. In addition, these sealing methods require expensive operating equipment that provide inconsistent and unpredictable hermetic seal failure. In addition, such sealing methods are not useful when it is desired to recover the membrane within the apparatus after use such as in the application of DNA synthesis on the membrane.
Accordingly, it would be desirable to provide a membrane support apparatus which can provide a consistently reliable seal about the membrane. In addition, it would be desirable to provide such an apparatus in a form which can be easily opened and closed so that a membrane can be easily positioned within the apparatus and can be easily removed from the apparatus. Furthermore, it would be desirable to provide such an apparatus which is capable of withstanding high internal pressure during use.